1. Field of the Invention
The present invention relates to electrical connectors and, more specifically to a contact planted on a dielectric housing of an electrical connector adapted to electrically mate an integral circuit (IC) package such as a central processing unit (CPU), with an electrical substrate such as a printed circuit board (PCB), wherein the contact is configured to have a long spring arm to improve spring characteristics thereof.
2. Description of the Prior Art
With the development of the connector industry toward the miniaturized, high-density and more reliable trends, generally, terminals or contacts secured on connectors, especially certain connectors used for electrically interconnecting an IC package, especially an land grid array (LGA) package with high-density leads or pads thereon with a PCB, are configured to be tiny and arranged in a high-density manner, e.g. a rectangular array, to catch up with the trends. This typically leads a problem, e.g. how to maintain good reliable electrical characteristics of the terminals or contacts of the connectors under these conditions.
One key factor to the above problem is focused on good normal force of the terminals or contacts which has direct and great effect on performance of the terminals or contacts. Except for material properties of the terminals or contacts, configuration or structures of the terminals or contacts play the important role in effecting normal force. Accordingly, optimized structures or configurations are increasingly becoming the useful and important weapon for manufacturers to prevail the connector market. Many ways to get better structures or configurations for the terminals of contacts have been invented so far.
One advanced way is disclosed in U.S. Pat. No. 5,984,693, assigned to Hon Hai who is also the assignee of the present invention. In this way, an LGA contact has a plate-like retention portion and a curved arm upwardly extending from a lower portion of the retention portion. An upright section is formed at an upper end of the arm, for electrically engaging a corresponding conductive pad of a CPU chip. With this configuration of the contact, the contact can have a relatively long arm, thereby facilitating improvement of contact characteristics thereof, namely, gaining good normal force.
However, the curved arm is disposed substantially within a corresponding contact-receiving passageway of a dielectric housing. Further, the arm has two main sub-arms extended in a horizontal direction vertical to a main surface of the retention portion. That is, the longer the arm is, the wider the horizontal projection of the arm becomes. Anyway, this will directly elongate a pitch of two adjacent contact-receiving passageways standing in a contact-receiving passageway row, thereby blocking the development of the contacts arranged in the housing toward the high-density trend.
Except for the above disadvantage, the upright section has an arc top surface with a topmost line left to electrically engage a bottom surface of the pad. When the contact mates with the chip, the upright section will be deflected aside. This is prone to result in engagement of only a point of the topmost line with the bottom surface of the pad. Thus, mating performance between the pad and the contact is liable to be in an inferior position.
In view of the above, it is strongly desired to provide a new LGA contact which overcomes the above-mentioned disadvantages.